Sam Stosur, the US Open champion, has led a robust response to Gilles Simon's claim that women do not deserve equal pay at grand slam tournaments by describing some men's matches as "boring". The Australian, who lost her second-round match to Holland's Arantxa Rus in three sets, said: "We deserve it. I think people come out and watch us play because they want to watch us play – there are a bunch of men's matches that go to five [sets] that are pretty boring to watch as well. It's not like a best-of-five match is better than a best-of-three."

Stacey Allaster, the chief executive of the WTA, was also critical of the No13 seeded Frenchman. "Tennis, including the grand slams, is aligned with our modern, progressive society when it comes to the principle of equality," she said.

"I can't believe in this day and age that anyone can still think otherwise. This type of thinking is exactly why the WTA was founded and we will always fight for what's right."

Simon, who will play Xavier Malisse in the second round, said: "We often speak of equal money, but it's something that doesn't work in sport. Tennis is the only sport where we have parity even though men's tennis remains more attractive than women's at this time."

Asked if she found the 27-year-old Frenchman's remarks offensive, Stosur said: "It's a little bit unfair. I think people come out and they want to watch a women's match or they want to watch a men's match. If it's an hour-and-a-half match, great. If it's a five-hour match, great. I don't think the duration means it's better. You want good quality. Like I said, not all men's matches are fun to watch either. Of course there are some women's matches that go pretty short too. That's where we're at. I don't think it's necessary to play best-of-five."

Ana Ivanovic, a former world No1 who beat Spain's María José Martínez Sánchez to reach the second round, said: "It's always been talked about, but we are different physiques. I think we earn our money – I mean, I was two and a half hours out there today."

France's Marion Bartoli, the 2007 singles finalist, agreed. "Over the whole year we are a long way from winning as much as the men – only in a few tournaments and grand slams. We are fully invested as much as them. The physical demands, training, investment on a personal level, are the same as theirs," she said.

Simon also criticised those tournaments beyond the majors that are now joint men's and women's events. Last week men and women played at Eastbourne and 's-Hertogenbosch and he said: "I am not against these tournaments, it's just that I think that today men's tennis is really ahead compared to women. When Rome became a joint tournament it was to save the women because I remember a final with 20 spectators."

Stosur, though, again disagreed with his stance. "I'm sure it's not because 20 people showed up for one final. It's an opinion that some people are going to have and others aren't going to agree. Everyone's going to have their opinion. For some reason it comes up every single year. It's a debate that's never going to finish."

Bartoli added: "The early rounds of men's matches do not attract many people either. Players who really attract spectators in men's tennis – there are only five to six."

Roger Federer, the six-time Wimbledon champion, was dismissive of the issue, saying: "Is this the first time I've heard this or is this an ongoing subject for years? I hope it doesn't become a big issue during Wimbledon. It's a debate that's out there ever since I guess the slams have made equal prize money. There's nothing you can do about it."

Sabine Lisicki accused Bojana Jovanovski of grunting so loudly it handed her an advantage. Lisicki beat the 20-year-old Serb 3-6, 6-2, 8-6 to make it into the third round, but only after she complained to the umpire, Mariana Alves, about the noise. "It was distracting," Lisicki said. "You usually hear the sound of the ball, but I couldn't hear it because of her grunting. But that's why we have the hindrance rule."

The women's tour's hindrance rule allows the umpire to take action, at their discretion, if, as the rule states, "a player hinders her opponent", but there was no punishment this time.